In a machining device such as a lathe, when machining a workpiece, for example as described in Japanese Unexamined Patent Application Publication No. 2002-59301, the workpiece is machined in a state where both end portions thereof are supported.
However, in the above supporting way, in a case where a workpiece W is an elongated workpiece, the workpiece W is deflected by its own weight as shown in FIG. 8, and thereby it is not possible to highly accurately machine the workpiece W. It is noted that in FIG. 8, reference numerals 100 refer to chucks for supporting both end portions of the workpiece W.
Therefore, for example, as described in Japanese Unexamined Patent Application Publication No. 2004-261935, the middle portion of the workpiece, as well as both end portions thereof, is supported by a center rest or the like and the workpiece is machined while preventing the middle portion from being deflected.